PR: Add spyder-kernels version for spyder 5.1.x

[ghost]

Pull Request

Pull Request Checklist

• [x] Read and followed this repo's Contributing Guidelines
• [x] Based your PR on the latest version of the correct branch (master or 4.x)
• [x] Checked your writing carefully for correct English spelling, grammar, etc
• [x] Described your changes and the motivation for them below
• [ ] Noted what issue(s) this pull request resolves, creating one if needed

Description of Changes

The documentation was missing a line for the spyder-kernels version of the current 5.1.* Spyder version, I've added that in the current pull request.

Issue(s) Resolved

Fixes #

[juanis2112]

@ccordoba12 I think we can merge this one. The test not passing is from a previous PR.

[CAM-Gerlach]

I just noticed that this table is apparently duplicated in the FAQ question that links here. To avoid having to constantly update and maintain both tables and risk one or both drifting out of sync/out of date, we should just link this table directly from that question (along with the question itself already linking to this section). I can open a followup PR.

[ccordoba12]

Agreed.